elasticsearch5.4.0 java开发注意事项

1，集群配置

1).node.master: true 指定该节点是否有资格被选举成为node，默认是true，es是默认集群中的第一台机器为master，如果这台机挂了就会重新选举master。 
2).node.data: true 指定该节点是否存储索引数据，默认为true。 
4.master和data同时配置会产生一些奇异的效果： 
1) 当master为false，而data为true时，会对该节点产生严重负荷； 需要提供一个性能比较好的机器
2) 当master为true，而data为false时，该节点作为一个协调者； 
3) 当master为false，data也为false时，该节点就变成了一个负载均衡器。 

属性:discovery.zen.minimum_master_nodes: 2

了解Zookeeper的话,这个配置就比较容易理解了; 数值取值为 (有资格当选为Master的节点个数/2+1), 这样做是为了防止脑裂现象, 防止某些主节点自成一个集群. 考虑到Zookeeper的一些配置, 主节点的个数最好是奇数个,并且不少于3个;但是会带来一个问题,如必须至少一半以上的主节点是可用的,如果不能满足这个要求,则系统就会崩溃.

注意：集群机器最好设置成2*n+1,这样设置的好处就是挂掉一半机器集群不会死掉。因为到了一半，ES集群就会挂掉。一般三台，五台，七台等等。

java开发：

由于ES版本对于java的要求比较严格，所以在服务器上的ES版本是多少，在pom文件中就引入版本多少的ES版本。

由于我是springboot开发，所以就举个例子。

1，pom.xml引入相关的jar包

<dependency>    <groupId>org.elasticsearch.client</groupId>    <artifactId>transport</artifactId>    <version>5.4.0</version></dependency><dependency>    <groupId>org.elasticsearch</groupId>    <artifactId>elasticsearch</artifactId>    <version>5.4.0</version></dependency>

还需要导入相应的log4j

<dependency>    <groupId>org.apache.logging.log4j</groupId>    <artifactId>log4j-api</artifactId>    <version>2.8.2</version></dependency><dependency>    <groupId>org.apache.logging.log4j</groupId>    <artifactId>log4j-core</artifactId>    <version>2.8.2</version></dependency>

2，application.properties

spring.data.elasticsearch.cluster-nodes=xxx.xxx.xx.xx:9300 #你自己的服务器ip和端口号spring.data.elasticsearch.cluster-name=elasticsearch #集群的名称

3,服务器启动加载类设置，主要是连接ES，不需要每次都连接，直接放在内存中就ok

package com.qz.quickSearch.clientConfig;import org.apache.log4j.Logger;import org.elasticsearch.action.index.IndexResponse;import org.elasticsearch.client.transport.TransportClient;import org.elasticsearch.common.settings.Settings;import org.elasticsearch.common.transport.InetSocketTransportAddress;import org.elasticsearch.transport.client.PreBuiltTransportClient;import org.springframework.beans.factory.DisposableBean;import org.springframework.beans.factory.FactoryBean;import org.springframework.beans.factory.InitializingBean;import org.springframework.beans.factory.annotation.Value;import org.springframework.context.annotation.Configuration;import java.net.InetAddress;import java.net.UnknownHostException;@Configurationpublic class ElasticsearchConfiguration implements FactoryBean<TransportClient>, InitializingBean, DisposableBean {    Logger logger = Logger.getLogger(ElasticsearchConfiguration.class);    @Value("${spring.data.elasticsearch.cluster-nodes}") //获取集群节点    private String clusterNodes;    @Value("${spring.data.elasticsearch.cluster-name}")//获取集群名称    private String clusterName;    private TransportClient client;    @Override    public void destroy() throws Exception {//销毁client        try {            logger.info("Closing elasticSearch client");            if (client != null) {                client.close();            }        } catch (final Exception e) {            logger.error("Error closing ElasticSearch client: ", e);        }    }    @Override    public TransportClient getObject() throws Exception {        return client;    }    @Override    public Class<TransportClient> getObjectType() {        return TransportClient.class;    }    @Override    public boolean isSingleton() {        return false;    }    @Override    public void afterPropertiesSet() throws Exception {        buildClient();    }//创建client    protected void buildClient() {        try {            PreBuiltTransportClient preBuiltTransportClient = new PreBuiltTransportClient(settings());            System.out.println("clusterNodes:" + clusterNodes);            if (!"".equals(clusterNodes)) {                for (String nodes : clusterNodes.split(",")) {                    String InetSocket[] = nodes.split(":");                    String Address = InetSocket[0];                    Integer port = Integer.valueOf(InetSocket[1]);                    preBuiltTransportClient.addTransportAddress(new InetSocketTransportAddress(InetAddress.getByName(Address), port));                }                client = preBuiltTransportClient;                System.out.println("client" + client);            }        } catch (UnknownHostException e) {            logger.error(e.getMessage());            System.out.println("连接错误");        }    }//设置集群名称seetings    private Settings settings() {        Settings settings = Settings.builder()                .put("cluster.name", clusterName).build();        client = new PreBuiltTransportClient(settings);        System.out.println("clusterName:" + clusterName);        return settings;    }}

4,调用service接口

package com.qz.quickSearch.service;public interface SearchService {    String search(String value);}

5,实现类

package com.qz.quickSearch.service.impl;import com.qz.quickSearch.clientConfig.ElasticsearchConfiguration;import com.qz.quickSearch.service.SearchService;import com.qz.quickSearch.utils.Constant;import com.qz.quickSearch.utils.JsonConvert;import com.qz.quickSearch.utils.MessageBean;import org.apache.log4j.Logger;import org.elasticsearch.action.search.SearchResponse;import org.elasticsearch.client.transport.TransportClient;import org.elasticsearch.index.query.QueryBuilders;import org.elasticsearch.index.query.SimpleQueryStringBuilder;import org.elasticsearch.index.query.WildcardQueryBuilder;import org.elasticsearch.search.SearchHit;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.stereotype.Service;import org.springframework.util.StringUtils;import java.util.*; @Servicepublic class SearchServiceImpl implements SearchService {    Logger logger = Logger.getLogger(SearchServiceImpl.class);    @Autowired    ElasticsearchConfiguration elasticsearchConfiguration;    String json = null;    /**     * demo，模糊查询     * @param value     * @return     */    @Override    public String search(String value) {        try {            if (!StringUtils.isEmpty(value)) {                TransportClient client = elasticsearchConfiguration.getObject();                 WildcardQueryBuilder wqb = QueryBuilders.wildcardQuery("message", "*" + value + "*");                //  SimpleQueryStringBuilder sqs = QueryBuilders.simpleQueryStringQuery(value);                SearchResponse response = client.prepareSearch().setQuery(wqb).setFrom(0).setSize(1000).execute().actionGet();                Iterator<SearchHit> iterator = response.getHits().iterator();                Map<String, String> mm = new HashMap<String, String>();                List<Map> list = new ArrayList<Map>();                while (iterator.hasNext()) {                    Map<String, Object> map = iterator.next().getSource();                    // mm.put("id", iterator.next().getId());                    mm.put("message", map.get("message").toString());                    list.add(mm);                }                if (list.size() > 0) {                    json = JsonConvert.convertToJson(new MessageBean(true, JsonConvert.convertToJson(list)));                } else {                    json = JsonConvert.convertToJson(new MessageBean(false                            , Constant.SEARCH_NO_DATA));                }            }        } catch (Exception e) {            logger.error(Constant.SEARCH_FALSE, e);            json = JsonConvert.convertToJson(new MessageBean(false                    , Constant.SEARCH_FALSE));        }        return json;    }}

6，controller类

package com.qz.quickSearch.controller;import com.qz.quickSearch.service.SearchService;import org.apache.log4j.Logger;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.stereotype.Controller;import org.springframework.web.bind.annotation.PathVariable;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.ResponseBody; @Controller@RequestMapping("/index")public class SearchController {    Logger logger = Logger.getLogger(SearchController.class);    @Autowired    SearchService searchService;    @RequestMapping("/search_{value}")    @ResponseBody    public String search(@PathVariable("value") String value) {        return searchService.search(value);    }}

7，页面html

<!DOCTYPE html><html lang="en" xmlns:th="http://www.thymeleaf.org"><head>    <link rel="stylesheet" href="/css/bootstrap.min.css"/>    <script type="text/javascript" src="/js/jquery.min.js"></script>    <script type="text/javascript" src="/js/bootstrap.min.js"></script>    <script src="/js/utils.js"></script>    <script src="/js/index.js"></script>    <title>潜智搜索</title></head><body><div style="margin-left: 30%;margin-top: 15%;">    <div class="row">        <div class="col-lg-6">            <div class="input-group">                <input type="text" class="form-control" id="searchText"/>                <span class="input-group-btn">                            <button class="btn btn-default" type="button" id="search">Go!</button>                        </span>            </div>        </div>    </div></div><div id="docTxt"></div><script type="text/javascript">          index.init();</script></body></html>

8，对应的index.js

index=function(){    var search=function(){        var text=$("#searchText").val();        var url="/index/search_"+text;        $.ajax({                type:"post",                url:url,                dataType:'json',                success:function (data) {                    $("#docTxt").empty();                    if(data.success){                        var dts=eval(data.message);                        if(dts.length>0){                            for(var i=0;i<dts.length;i++){                               var doc=$("<a href='javascript:;' id='"+dts[i].message+"'>"+dts[i].message+"</a></br>");                                $("#docTxt").append(doc);                            }                        }else{                            alert(data.message);                        }                    }else{                        alert(data.message);                    }                },                failure:function(data){                     alert(data);                }            });     };    return {        init:function(){            $("#search").bind("click",function(){                search();            });            $("#searchText").bind("keydown",function(e){                if(e.keyCode==13){                   search(); //处理事件                }            });        }    }}();

至此，一个简单的demo就完成了，如有不懂可以联系我。

wechat: